Table of Contents
What is microwave ceramics?
Microwave dielectric ceramics improve the size of devices and the packaging density of microwave integrated circuits. For this reason, it is widely used for the microwave filters and circuit boards in the base station of mobile commucations and satellite communication systems.
Is ceramic microwave transparent?
Most electrically insulating ceramics such as alumina, MgO, silica, and glasses are transparent to microwaves at room temperature, but, when heated above a certain critical temperature Tc , they begin to absorb and couple more effectively with microwave radiation.
What is the microwave frequency used for ceramic processing?
Conventional microwave processing of ceramics, using 2.45 GHz sources, has seen extensive research . Use of this fi~quency has been a result of availability of low cost, moderate-high power sources and related technology, from use of frequencies in this range for radar and food processing.
How does microwave sintering work?
In microwave sintering, the energy that is delivered however penetrates through the material through molecular interactions, which capitalizing on the electromagnetic field renders the energy transfer faster than the conventional process.
What is microwave sintering furnace?
High Temperature Microwave Sintering Furnace Microwave Sintering Furnaces are one of the very effective solutions for sintering various materials. This is an advanced Microwave Sintering Furnace with State-of-the-Art Control system and high microwave power to sinter larger samples.
Is a microwave transparent?
Nowadays, several research groups are working on microwave heated melting furnaces for oxidic materials and even metals [1, 2]. Microwaves are electromagnetic waves with frequencies between 300 MHz and 300 GHz. Materials with very low loss factors are called “microwave transparent” [3].
How does spark plasma sintering work?
Spark plasma sintering (SPS) (Nygren and Shen, 2003), also known as field assisted sintering technique (FAST), uses an electrical current (DC, pulsed DC, or AC) which is passed through a conducting pressure die (graphite) and, if the material has reasonable electrical conductivity, through the ceramic itself.
What are the requirements for liquid phase sintering?
Therefore, for liquid-phase sintering, the requirements include that the liquid wets the solid particles, there is sufficient liquid present, and the solid is soluble in the liquid.
What is the process of sintering?
Sintering is the process of fusing particles together into one solid mass by using a combination of pressure and heat without melting the materials. Common particles that are sintered together include metal, ceramic, plastic, and other various materials.
What is the microwave frequency commonly used in microwave sintering synthesis?
It is based on the ability of a material to absorb the electromagnetic energy which depends mainly on electrical conductivity, complex permittivity, and complex permeability of the materials. The most commonly used frequency in MW sintering is 2.45 GHz.
What is solid state sintering?
Abstract. Solid-state sintering is the bonding and densification of particles by the application of heat below the melting point of a material. During sintering, the free surface area of the compact decreases, and this is normally accompanied by an increase in the density.
Can microwaves pass through glass?
Microwaves have three characteristics that allow them to be used in cooking: they are reflected by metal; they pass through glass, paper, plastic, and similar materials; and they are absorbed by foods.
Is plastic transparent to microwave?
Plastic containers that are microwave safe are not intended for ovens, stovetops, or other browning elements. Among commonly used plastics for labware Polymethylpentene and Polysulfone are the most transparent to microwaves.
Can microwaves pass through wood?
Figure 3 shows that energy efficiency of the single-port feeding mode is the highest, which is because the microwave feeding direction is oblique; microwave reflected several times in the microwave cavity; microwave can be fully absorbed by wood.
What is field assisted sintering?
A new type of sintering, called Field Assisted Sintering Technology (FAST), uses a pulsed or continuous high density electric current delivered through the pressure mold and the powder to cause very rapid heating and dramatically shorter sintering times.
What is hot press sintering?
Hot pressing is a high-pressure, low-strain-rate powder metallurgy process for forming of a powder or powder compact at a temperature high enough to induce sintering and creep processes. This is achieved by the simultaneous application of heat and pressure.
What is meant by liquid phase sintering?
Liquid phase sintering (LPS) is a process for forming high performance, multiple-phase components from powders. It involves sintering under conditions where solid grains coexist with a wetting liquid. Many variants of LPS are applied to a wide range of engineering materials.
What is liquid phase sintering and its working process with advantages?
Main advantages of this production method are low sintering temperatures, fast densification, high final densities and resulting microstructures often providing mechanical or physical material properties superior to solid state sintered materials.
What are the advantages and disadvantages of liquid phase sintering?
The potential disadvantages of liquid phase sintering include high distortion, deterioration of mechanical properties due to the solidification of brittlephases along grain boundaries and/or grain growth during sintering, the limitation of the final part in high-temperature applications, and thermodynamic factors, Jul 29, 2019.
What is the purpose of sintering process?
Sintering is a heat treatment commonly used to increase the strength and structural integrity of a given material. Powder metallurgy processes use sintering to convert metal powders and other unique materials into end-use parts.
What is purpose of sintering?
The purpose of sintering is to impart strength and integrity to the material. During the sintering process the temperature must be kept below the melting point of the constituent materials.
Why sintering process is important?
The sintering process can determine the optimal structure and properties of the desired finished product. These include the material’s strength, electric and thermal conductivity, ductility, and toughness. Controlling the sintering process is, therefore, key to the entire powder metallurgy process.
Which transport mechanisms occur during solid state sintering?
1 Mechanisms of solid-state sintering. Sintering of crystalline materials can occur by at least six mechanisms or paths: vapor transport (evaporation/condensation), surface diffusion, lattice (volume) diffusion, grain boundary diffusion, and plastic flow.
What is sintering in metallurgy?
Sintering is a heat treatment applied to a powder compact in order to impart strength and integrity. The temperature used for sintering is below the melting point of the major constituent of the Powder Metallurgy material. Reduction of the surface oxides from the powder particles in the compact.
What are the main driving forces during actual solid state sintering?
The driving force for the sintering process is the reduction in surface free energy of the particle. This reduction is achieved by diffusional transport of material from the centers of particles to the particle–particle necks. As individual particles fuse, the surface area of the particles decreases.
